Catalytic treatment of petroleum hydrocarbons



April 6, 1943.

GATALYTIC TREATMENT OF PETROLEUM HYDROCARBONS P. S. DANNER ET AL FiledApril 27, 1957 Patented Apr. `6, 1943 CATALYTIC' TREATMENT 0F PETROLEUMHYDROCARBONS Philip S. Danner and Calif., assignors to Robert C.Mithoff, Berkeley, Standard Oil Company of California, San Francisco,Calif., a corporation of Delaware Application April 27, 1937, Serial No.139,208

' 12 Claims. (Cl. 19652)f The invention relates to catalytic treatmentof petroleum hydrocarbons boiling within the range of ordinary gasolineto increase the combustion eiilciency or octane number thereof and tostabilize the hydrocarbons against gum formation or color deterioration.

The invention involves the discovery of catalysts and operatingconditions which effect an increase in the octane number of straight rungasolines without material alteration of the boiling point range of thefuel. 'I'he discovery of operating conditions which minimize catalystpoisoning and which increase the life of the catalyst many fold alsocomprises an important feature of the invention.

Stabilization of gasolines against formation of gums and color bodieswithout decreasing the octane number of the fuel is regarded as animportant feature of the invention.

Accordingly, an object of this invention is to provide a process ofcatalytically treating petroleum hydrocarbons boiling within thegasoline range to increase the anti-knock value thereof withoutmaterially altering the boiling range of the product.

Another object of the invention is to provide a two-stage catalyticprocess for treating gasolines; the first stage producing hydrocarbonswhich increase the octane number of the fuel and the second stagestabilizing the converted gasoline against gum formation and colordeterioration.

An additional object of the invention is to provide a method ofinhibiting catalyst poisoning in a catalytic process for producinghydrocarbons of high octane number from hydrocarbons of lower octanenumber.

A further object of the invention is to control the production of highoctane number hydrocarbons during catalytic treatment of gasoline sothat fuels having a constant octane number are produced despitevariation in catalyst activity.

To provide a process of inhibiting deposition of Y gums, carbon and thelike on the catalyst during vapor phase catalytic treatment of gasolineand to simultaneously avoid interference with formation of hydrocarbonshaving a high octane number, comprises another object of the invention.

A further object is to provide a two-stage catalytic process utilizingthe same type of catalyst first to increase the octane number and thento stabilize the reformed gasoline against gum formation and colordeterioration.

The process of this invention should not be confused with other types ofprocesses, such as catalytic cracking, destructive hydrogenation, or

#catalytic desulfurization which require diiferent conditions ofoperation, involve different chemical reactions, and which producedifferent results.

Vapor phase catalytic cracking or destructive hydrogenation processesutilize temperatures and/or pressures higher than are suitable for ytheprocess employed in this invention.

Vapor phase catalytic desulfurization is carried out at temperaturesbelow approximately 750 F. Such temperatures are inoperative for thepurpose of producing hydrocarbons having high octane numbers as hereindisclosed.

The process of this invention avoids many of the diiiiculties anddisadvantages encountered in the practice of prior known processes forreforming gasolines to increase the octane number. For example,non-catalytic thermal reforming processes have the disadvantage ofproducing hydrocarbons too light or too heavy to be used in gasolines,often to the extent that distillation is necessary to remove low andhigh boiling products formed by the thermal treatment. The presentinvention not only avoids this difficulty but also produces a gasolinewhich has less tendency to form gum or color bodies.

One of the principal difficulties which have been encountered in knowncatalytic dehydrogenating processes is catalyst poisoning and consequentshort catalyst life. By utilizing the particular combination ofoperating conditions and catalysts of the present invention, poisoninghas been inhibited to such an extent that `catalyst life is increasedmany fold. Dehydrogenating processes have also been carried out at suchhigh temperatures (as, for instance, at 650 C. in Example 3 of FrenchPatent No. 629,838 to I. G. Farbenindustrie), that both acceleratedcatalyst poisoning and material alteration of the boiling range of theproduct result.

The preferred embodiment of this invention involves a two-stage process.In order that the chemical changes occurring in each stage may be moreclearly understood the conditions of operation of the two stages,together with the chemical changes so far as they are understoodresulting therefrom, will. be described separately.

The drawing illustrates a flow sheet of the two-stage process of thepresent invention.

The rst stage involves the production of hydrocarbons having high octanenumbers from hydrocarbons of lower octane number. One of the mostcritical'featurcs of this first stage of the operation is temperaturecontrol. The temperature of the catalyst should be maintained fOr themost part within the range of 850 F. to

950 F. and preferably at approximately 900 F. At the beginning ofoperations with a fresh catalyst, it is possible to use temperatures aslow as 825 F. During the final portion of an operation with a catalystwhich has become sluggish, the temperature can be raised to an uppermaximum of 1025 F. By controlling temperature in this manner and bycoordinating temperature with catalyst activity (that is, increasingtemperature as catalyst activity decreases) soi that the ratio Aofvolume of fixed gases formed to amount of hydrocarbons treated ismaintained approximately constant, a treated gasoline having the sameoctane number at the beginning and end of an operating cycle, isobtained. At temperatures below 825 F. the catalysts are not suf-.ciently active to increase the octane number of the vapors to anysubstantial extent. Temperatures above 950 F. produce acceleratedcatalyst poisoning and short catalyst life. 'I'he temperature rangespecified is therefore of critical importance.

Catalysts found to be active and best suited for the above first stageof operation are bauxite, precipitated alumina, zinc oxide, stannicoxide,

l zirconium oxide and thorium oxide.

It has been discovered that introduction of steam along with thehydrocarbon vapors.` very greatly increases the active life of the:above catalysts without interfering with the formation of hydrocarbonshaving high octane number. For example, when one to two molecules of'water vapor is introduced for each ten molecules `of hydrocarbon vapor(using the average molecular weight of the hydrocarbons in the vaporsbeing treated as the basis for calculation) the catalyst life wasincreased in some cases as much as tenfold over that obtained under thesame operating conditions without the introduction of steam. Although ithas been found that water vapor inhibits catalyst poisoning withoutinterfering with formation of hydrocarbons of high octane number, thechemical mechanism of this action has not been established. So far asknown to applicants the selective action of water vapor on catalystpoisons rather than on the hydrocarbons of high octane number which arebeing formed has no adequate theoretical explanation. Having oncediscovered this empirical and unpredictable result, the partial pressureor proportion of water vapor can be adjusted by simple tests to obtainmaximum catalyst life and minimum interference with formation of thedesired hydrocarbons of high octane number. The proportions previouslyindicated have been found satisfactory. These proportions may of coursevary with the stock being treated, the catalyst used and the conditionsof operation.

The use of pressure is unnecessary in the operation of the aboveprocess. Within the broad aspects of the invention, however, pressuresup to approximately 500 pounds per square inch may be utilized. The useof superatmospheric pressure possesses some advantage in the separationof fixed gases from the condensed vapors, in scrubbing the dissolvedhydrogen sulfide from the condensate, and in increasing the capacity ofthe catalyst chamber. Insofar as the essential feature of increasing theoctane number of the treated vapors is concerned, atmospheric pressuresare preferred.

The following specific example is given to illustrate the effects oftreatment at temperatures of 82,5 to 1025 F. according to thisinvention.

A California straight-run gasoline distillate was vaporized and thevapors passed at atmospheric pressure through a bed or body of bauxiteheld at 918 F. The hydrocarbons were fed through the catalyst at a rateof 1 gallon of liquid fuel charged per 1.4 cubic foot of catalyst spaceper hour. The following tabulation shows the chemical changes and theimprovement in octane number resulting from this treatment.

gas were produced per gallon of gasoline charged. This gas containedabout hydrogen at the beginning of the run, but the hydrogen contentdropped to about 50% after 80 to 100 hours of operation without catalystrevivication.

The second stage of the processconsists in passing gasoline from the rststa'ge of treatment, with or without the gases formed therein, in vaporphase over a stabilizingcatalyst. Temperature is of critical importancein this second stage of operation. From the standpoint of stability ofthe product against gum formation the temperature should be betweenapproximately 570 F. and 660 F.; however, temperature as low as 525 F.and as high as 800 F. are operative to increase the stability of thefuel and may be utilized. Feed rates of 50 to 100 gallons of liquid fuelper hour per ton of catalyst produce satisfactory results.

Catalysts found to be active for stabilizing the treated gasoline aretungsten oxide, alumina, bauxite and Florida clay. The preferredcatalysts are either alumina or bauxite, since these materials are amongthe more active and satisfactory ones used to produce hydrocarbons of ohigh octane number in the first stage of the process. One importantdiscovery which this invention utilizes is that when these catalystshave become sluggish as stabilizing catalysts in the lsecond stage ofthe process, they are still active to produce hydrocarbons of highoctane number when utilized in the first stage of treatment. By adoptingthe procedure of using the catalyst first to stabilize the fuel and thento catalytically convert low octane number hydrocarbons to high octanenumber hydrocarbons a single body of catalyst is used twice, that is, inboth the vfirst and second stage of operation without an interveningregeneration step being necessary.

The exact chemical nature of the phenomenon which occurs during thestabilization step has not been established. We have observed that thereis a reduction of 10% or more in the amount of unsaturated compoundspresent in the fuel and a corresponding increase in the amount of morestable hydrocarbons, principally aromatics and' naphthenes. There alsoappears to be a change in the form of the remaining unsaturates asindicated by their increased stability against gum formation and againstpolymerization when the fuel is treated with sulphuric acid. I

The following analysis shows changes which occur during the presentprocess. These analyses were made on the same fuel, first beforetralmcnt, then after treatment according to Aiwr ist Untrcaicd Agt'gtand '.d

` stage OctaneNo 56 (i7 Unsaturatas". pirccnt 18. il 7. 2 Aromatics .lo7.0 15.2 Naphthcuos do... 48 47.1 Paraiiins .dom. 26.2l 30.5 Miligramsoi gum per 100 cc.

ill 31H (i2 A. I. I. gravity l 50.8 40.0

These data indicate that unsaturates are converted to aromatics as shownby the decrease from 18.8% to 7.2% of unsaturates and theinf crease from7% to 15.2% of aromatics.

A gasoline which gums or discolors readily is rendered completelycolor-stable and gum stable by the above described stabilizationtreatment. Further refinement is not necessary for most purposes sincethe product is water-white and completely satisfactory. This feature isillustrated by the data from gum stability tests recorded in the abovetable. Before stabilization the fuel formed 331 mgs. of gum and afterstabilization only 62 mgs. of gum, in a standardized test.

When specifications as to extremely low sulfur content must be met it issometimes necessary to subject the fuel to further refining treatments,as for instance, treatment with sulphuric acid.

'I'he stabilization treatment produces a gasoline which requires lesssulphuric acid for a given degree of refinement than is required bystraight cracked or reformed gasolines. Naphtha stabilized according tothe present process and treated with a given amount of sulfuric acid,yields a treated naphtha of higher gasoline content than do cracked orreformed naphthas. 'Ihese facts are illustrated by the data fromtreatment of a crude vapor phase naphtha which had been passed overbauxite at 570 F.

Original Processed naphtha naphtha Unsaturation 7i'- 69 louncls of coldlili llo. l|'-S() por gallon of naphtha required io prorluw gasoline of(M50/i, sulfur contont 0.75 0.5 Overall gasoline yclii. 711. 80. ii

The increase-in the stability against polymerization of the unsaturatesremaining in the fuel is illustrated by the following data: Anunprocessed naphtha was treated with 0.5 lb. of 66 B. sulphuric acid pergallon of fuel. This treatment caused a polymerization loss of 8.3%.Another portion of this same fuel was stabilized by treatment at 660 F.according to the present invention and then treated with the same amountof sulphuric acid underthe same conditions. The polymerization loss wasreduced to 1.3%. This represents a decrease of approximately 85% in theamount of polymerization.

It should be noted that the second stage of the process of thisinvention effects stabilization of the high octane hydrocarbons withoutsubstantially reducing the octane number of the fuel. It has been foundthat the stabilization treatment may either increase or decrease theoctane. number of the fuel to a minor extent,'depending upon theconditions of treatment and the characteristics of the distillate beingtreated. To

illustrate these factors the following specific examples are given: Acrude California natural gasoline having an octane number of 56 was runthrough the rt stage of treatment and its octane number increased to'70. This product was then separated into two fractions by distillation.The most volatile fraction, the first ,over, was passed over 1700 cc. ofbauxite at 570 F. at the rate of 400 cc. of liquid fuel per hour. Theoctane number of this stabilized fraction was 67. The less volatile 50%of the original gasoline was stabilized in exactly the same manner. Theoctane number of the second fraction was 71. It is thus seenthat theoctane number of the more volatile fraction was decreased somewhat andthat of the less volatile fraction increased. The net change on theentire fuel is therefore relatively small. To further exemplify theutility of this invention tetraethyl lead fluid as sold onl the marketwas added to a gasoline which had been .treated by the two-stage processherein described The increase in octane number resulting from theaddition of various amounts of thetetraethyl lead is shown in thefollowing table:

l Octane No. Original fuel-. 67 Original fuel 2 cc. per gal. tetraethyllead fluid g 75 Original fuel 4 cc. per gal. tetraethyl lead fluid '77Original fuel 6 cc. per gal, tetraethyl lead uirl '79 Original fuel 8cc. per gal. tetraethyl lead fluid Original fuel -i- 10 cc. per gal.tetraethyl lead fluid 82 In regard to the catalyst used in the processof this invention, it is noted that even though catalyst life has beenincreased many times, the catalytic materials do eventually becomepoisoned with carbon, gums and the like. The catalyst must beregenerated after long periods of opbons and intermittently regeneratingthe catalystv is to provide a series of separate catalyst chambersconnected by valve controlled conduits so that the chambers can be usedin rotation. For example, when three chambers are provided there will bethe following periods of operation involved in a complete cycle:

lst periml-Fntalyst chamber #l at S25-800 ll'.

Catalyst chamber #2 at 825-1025" F. Catalyst chamber #3 catalystrevivifcniion. 2nd period-Catalyst chamber #3 at E25-800 1".

Catalyst chamber it] at S25-1025* l. Catalyst chamber #2 natal si:revivil'caiion. 311i polimi-Catalyst chamber #2 at 52. M800 F.

("ntnlyst chamber :d3 at 825-1025 F. Catalyst chamber #l catalystreviviflnatinn. 4thperiod-Sunmlas lst period and begins repetition oi'(gwl.

From the above tabulation it is evident that a particular body ofcatalyst passes through a cycle involving, first, use in the secondstage of -the process at temperatures of 570-660 F. to stabilize thehydrocarbon vapors and, second, use in the rst stage of the process attemperatures of from 825-1025 F. to convert incoming low octane numerhydrocarbons to high octane number hydrocarbons.

Another method of providing a continuous process is to supply activecatalyst to one end of a catalyst chamber while removing exhausted orinactive catalyst from the other end. In this latter instance thetemperature of the catalyst at the end where the fresh catalyst isintroduced will be maintained at 525 to 800 F. and the temperature atthe opposite end of the catalyst chamber maintained at from 825 to 1025F. The hydrocarbons to be treated ow in at the high temperature end,through the chamber and out, at the low temperature end. Thetemperature; gradient may be maintained and controlled by suitableheating and cooling coils or by introduction of live steam into thevapors at points intermediate the ends of the catalyst chamber. .A1-though the two-stage process can be carried lout in a single catalystchamber, as described, we prefer to keep thc two stages of operationseparate and effect each stage of treatment in a separate chamber. Thelatter method is more exlble and casier to control. Low pressure steamprovides an effective cooling medium since its temperature may be as lowas 212 F. y

The process steps of the preferred specific embodiment of the inventionas hereinabove described may be summarized as follows:

(a) Vaporizing petroleum hydrocarbons of substantially gasoline boilingpoint range;

(bl Passing the vapors, together with Water u vapor, at a moderate rateover bauxite at ternperatures between 850 F. and 950 F. for vthe majorportion of a catalyst operating period;

(c) Controlling the temperature of the catalyst so that the ratio offixed gases to vapors treated is maintained approximately constant;

(d) Passing the hydrocarbon vapors over bauxite at temperatures from 570to 660 F.;

(e) Condensing the vapors of substantially gasoline boiling point range;

if) Separating xed gases from the condensed vapors;

(y) Utilizing the catalyst which `has become sluggish at 570 to 660 F.for the treatment at 850 to 950 F.;

(h) Regenerating the catalyst by blowing with ail` or air and steam.

As previously indicated a number of catalysts are operative in theprocess of this invention. In order to compare the relative efficiencyof catalysts and their activity in converting low octane numberhydrocarbons to high octane number hydrocarbons, straight run gasolinewas passed through various catalyst bodies at the rate of one gallon perhour per .07 cubic feet (2000 cubic centimeters) of catalyst. Thetemperature of treatment was maintained at 900 F. and the catalystactivity compared by measuring the volume of fixed gases produced. Freshartificial alumina appeared to be the most highly active of all of thecatalysts tried. Bauxite was only slightly less active initially butshowed greater resistance to poisoning after continued use. Starmicoxide, zinc oxide (dry process), zirconium oxide, thorium oxide, andalkalinized zinc oxide are all sat isfactory active catalysts, but arenot as active as the aluminum oxide catalysts.

Catalysts found to be less active than the above are molybdic oxide,manganese dioxide, zinc chromite, a mixture of aluminum, chromium andmolybdenum oxides, precipitated zinc oxide, and precipitated aluminawhich had been heated to 1600 F.

Various methodsof preparing the above catalysts are within the skill ofthe art. The following illustrations are given to exemplify one methodwhich has been found to be satisfactory.

Bauxite was ground and screened to 30-60 mesh.

Aluminum hydroxide was precipitated from aluminum chloride solution withammonia, washed, dried, and groundeto 30-60 mesh to give artiiicialalumina.

Commercial zinc oxide powder produced by calcining or burnlng,.was wetwith a 5% solution of agar-agar, dried, and ground to 30-60 mesh. Thiscatalyst is designated in the presentspecication as "Dry process zincoxide."

Basic zinc carbonate was precipitated from zinc sulfate solution withsodium carbonate, filtered, Washed, and dried. This precipitate was thenmoistened with enough potassium carbonate solution to give 1% as muchKzO as ZnO, dried, and ground to 30-60 mesh. This product is termedalkalinized Zinc oxide in the present application.

Sponge tin was heated with excess concentrated nitric acid to forminsoluble stannic oxide. The mixture was dried and screened to 30-60mesh.

Zirconium oxidewas prepared by sintering a commercial zirconium oxidepowder with agaragar and grinding to 30-60 mesh as in the case of dryprocess zinc oxide.

Thorium carbonate was precipitated from thorium nitrate solution withsodium carbonate, l- Itered, washed, dried, heated to transform it tothe oxide, and ground to 30-60`mesh.

As previously noted the above methods of catalyst preparation are merelyto be regarded as one illustrationof the many suitable methods which maybe adopted. i

Reference has been made throughout the present specification toregeneration of the catalyst.

When the catalyst becomes poisoned after long continuous use, it may beregenerated without removal from the catalyst chamber, by burning withair. The hydrocarbon vapors are first swept from the catalyst chamberwith steam, then air or a mixture of steam and air is admitted to thecatalyst chamber until the combustion of the poisoning deposits iscomplete. Precautions should be taken to maintain the air flow ratebelow that which causes local overheating with consequent damage to bothapparatus and catalyst` Regeneration by this method renews activity tosubstantially that of a fresh catalyst.

Our process nds its greatest utility in the treatment of straight-rungasolines having a boiling range of from 200 to 400 F. and moreparticularly to such straight-run gasolines containing 20% or morenaphthenic hydrocarbons. It is particularly effective for the treatmentof California or Mid-Continent straight-run gasolines and for treatmentof aluminum chloride gasolines produced by processes such as in U. S.Patents Nos. 1,193,540 and 1,127,465. The process is also applicable toparailnic gasolines and can be applied with less advantage to crackedgasolines.

Gasoline treated by the process of this invention shows greatersusceptibility to increase in octance number by addition of leadtetraethyl than the same gasoline treated to give the same octane valueby non-catalytic thermal reforming processes. This may be due to thefact that as much as of the sulfur is removed by our catalytic treatmentat the same time reforming of the hydrocarbons is occurring. Gasolinetreated by non-catalytic reforming processes is also generally lessdesirable as to color, odor and stability than is gasoline from ourparticular catalytic treatment.

The provision of suitable apparatus for carrying out ourvprocess isregarded as withinthe skill of the petroleum technician. Common thegroup consisting of bauxite, precipitated alumina, zinc oxide. stannicoxide, zirconium oxide and thorium oxide, whereby the antiknock value ofsaid fuel is catalytically increased without material alteration of theboiling range thereof; and then stabilizing said fuel against forms ofcatalyst chambers, support for catalyst beds, heating and cooling meansto control the temperature of the catalyst `bed and the' temperature ofthe petroleum vapors, may be utilized. The apparatus disclosed in thepatent to Harrison et al. 2,031,600 comprises an example of a known formof apparatus suitable for carrying out the process of this invention.

The scope of this invention is not limited to the specific examplesherein disclosed but comprehends variations and equivalents includedwithin the spirit and terms of the appended claims.

We claim:

l. A process of catalytically treating and stabilizing a hydrocarbonfuel boiling within the range of gasoline which comprises:dehydrogenating hydrocarbons of low octane number, without cracking saidfuel sufficiently to substantially alter the boiling range thereof, bypassing said fuel in vapor phase at temperatures of from approximately825 F. to 1025 -F. and in the absence of substantial quantities of addedhydrogen over a metal oxide catalyst capable of catalyzingdehydrogenation reactions without concurrently producing substantialcracking, whereby the anti-knock value of said fuel is catalyticallyincreased without material alteration of the boiling range thereof; andthen stabilizing said fuel against gum formation, without substantialadverse effect upon the octane number thereof, by passing said fuelvapors over a metal oxide catalyst selected from the group consisting oftungsten oxide, alumina and bauxite at a temperature of fromapproximately 525 F. to 800 F.

2. A process of treating petroleum hydrocarbon fuels having a boilingrange of from approximately 200 F. to 400 F. which comprises:dehydrogenating hydrocarbons of low octane number, without cracking saidfuel sufficiently to substantially alter the boiling range thereof, bypassing said hydrocarbons in vapor phase in the absence of substantialquantities of added hydrogen over` a metal oxide catalyst capable ofcatalyzing dehydrogenation reactions without concurrently producingsubstantial cracking; maintaining said fuel vapors and catalyst at fromapproximately 825 F. to 1025 F. whereby said fuel is dehydrogenatedwithout substantial alteration of the boiling range thereof; and thenstabilizing said fuel against gum formation, without substantial adverseeffect upon the octane number thereof, by passing said fuel vapors overa metal oxide catalyst selected from the group consisting of tungstenoxide, alumina and bauxite at a. temperature of from approximately 525F. to 800 F.

3. A process of catalytically treating and stabilizing a hydrocarbonfuel boiling within the range of gasoline which comprises; reforminghydrocarbons of low octane number, without cracking said fuelsufficiently to substantially alter the boiling range thereof, bypassing said fuel in vapor phase at temperatures of from approximately825 F. to 1025 F. and in. the absence of substantial quantities of addedhydrogen over a metal oxide catalyst selected from gum formation,without substantial adverse effect upon theoctane number thereof. bypassing said fuel vapors over a metal oxide catalyst selected from-'thegroup consisting of tungsten oxide, alumina, and bauxite at atemperature of from approximately 525 to 800 F.

4. A` process of catalytically treating and stabilizing ahydrocarbonfuel boiling within the range of gasoline which comprises:dehydrogenating hydrocarbons o f low octane number, without crackingsaid fuel sufficiently to substantially alter the boiling range thereof,by passing said fuel in vapor phase at temperatures of fromapproximately 825 F. to 1'025 F. and in the absence of substantialquantities of added hydrogen over an aluminum oxide catalyst capable ofcatalyzing dehydrogenation reactions without concurrently producing`substantial cracking, .whereby the anti-knock value of said fuel iscatalytically increased without material alteration of the boiling rangethereof; and then stabilizing said fuel Vagainst gum formation, withoutsubstantial adverse effect upon the octane number thereof, by passingsaid fuel vapors over an aluminum oxide catalyst at a temperature offrom approximately ozb F. to uu F.

5. A process of catalytically treating and stabilizing a hydrocarbonfuel boiling witnm the range of gasoline which comprises:rdehydrogenating hydrocarbons ol' low octane number, witnout crackingsaid I'uel sufficiently to substantially alter the boiling rangethereof, by passing said fuel in vapor phase at temperatures of fromapproximately 825 F. to 1025 F. and in the aosence of substantiallyquantities of added hydrogen over a bauxite catalyst capable ofcatalyzing dehydrogenation reactions without concurrently producingsubstantial cracking, whereby the antiknock value of said fuel iscatalytically increased without material alteration of the boiling rangethereof; and then stabilizing said fuel against gum formation, withoutsubstantial adverse effect upon the octane number thereof, by passingsaid fuel vapors over a bauxite catalyst at a temperature of fromapproximately 525 F. to 800 F.

o'. A process of catalytically treating and stabilizing a hydrocarbonfuel boiling within the range of gasoline which comprises:dehydrogenating hydrocarbons of low octane number, without cracking saidfuel sufficiently to substantially l alter the boiling range thereof, bypassing said fuel in vapor phase at temperatures of from approximately825 F. to 1025u F. and in the absence of substantial quantities of addedhydrogen over an aluminum oxide catalyst capable of catalyzingdehydrogenation reactions without concurrently producing substantialcracking, whereby the anti-knock value of said fuel is catalyticallyincreased without material alteration of the boiling range thereof; thenstabilizing said fuel against gum formation, without substantial adverseeffect upon the octane number thereof, by passing said fuel vapors overan aluminum oxide catalyst at a temperature of from approximately 525 F.to 800 F.; and, when the catalyst in said stabilizing treatment at 525F. to 800 F. has become substantially inactive at this temperature,utilizing said aluminum oxide to catalytically instabilizing hydrocarbonfuels boilingY within the range of gasoline. comprising vaporizing saidfuel, catalytically increasingthe anti-knock value of said fuel, withoutsubstantial alteration of the boiling range thereof, by passing saidfuel vapors over a catalyst capable of catalyzing dehydrogenationreactions without concurrently producingsubstantial cracking, wherebythe anti-lfnckv value of said fuel is catalytically increasedy withoutmaterial alteration of the boiling range: the steps of maintaining saidcatalyst at a temperature of from approximately 850 F. to 950 F. for amajor portion of the duration of said catalytic treatments andstabilizing said fuel against gum formation, without material reductionof the octane number thereof, by passing said fuel vapors after saidcatalytic treatment over bauxite at a tzxlperature f from approximately525 F. to 8 F.

11. A process of treating petroleum hydrocarbon fuels boiling within therange of gasoline which comprises: catalyzing conversion of hydrocarbonsof low octane number to hydrocarbons of high octane number, Withoutproducing sufficient cracking of said fuel to substantially alter theboiling range thereof, by passing said hydrocarbons in vapor phase overa metal oxide catalyst capable of catalyzing dehydrogenation reac-1tions without concurrently producing substantial cracking, whereby theanti-knock value of'said fuel is catalytically increased withoutmaterial alteration of the boiling range; maintaining said fuel vaporsand catalyst at from approximately 825 F. to l025 F. during saidcatalytic treatment; inhibiting poison of the catalyst, withoutsubstantially interfering with said conversion, by contacting saidcatalyst simultaneously with steam and with said hydrocarbon vapors; andthen stabilizing said fuel against gum formation,

AWithout substantial reduction of the octane number thereof. by passingsaid vapors over a metal oxide catalyst selected from the groupconsisting of tungsten oxide, alumina and bauxite at a temperature offrom approximately 525 F. to 800 F.

l2. In a process of treating petroleum hydrocarbon fuels boiling withinthe range of gasoline which comprises catalytically increasing theantiknock value of said fuels, Without substantial alteration of theboiling range thereof, by passing said hydrocarbons in vapor phase overa metal oxide catalyst capable of catalyzing dehydrogenation reactionswithout concurrently producing substantial cracking, whereby theanti-knock value of said fuel is catalytically increased witnoutmaterial alteration of the boiling range: the steps of maintaining saidcatalyst at a temperature of from approximately 850 F. to 950 F. for amajor portion of the duration of said catalytic treatment and thencorrelating temperature with catalyst activity by increasing thecatalyst temperature from 850 F. to no more than approximately 1025 F.at a rate suliicient to maintain the ratio of fixed gases formed toamount of fuel treated substantially constant throughout an operatingcycle.

PHHJP S. BANNER. ROBERT C. MITI-IOFF.

